This application describes a competitive renewal for an additional five years of funding for the confocal scanning laser ophthalmoscopy (CSLO) ancillary study to the Ocular Hypertension Treatment Study (OHTS). The overall goal of this study is to determine the effectiveness of CSLO to objectively and quantitatively detect glaucomatous changes of the optic disc in ocular hypertensive patients and to assess the effect of ocular hypotensive treatment on optic disc topography. Specific Aims: 1. Effect of treatment on change in optic disc topography. To estimate the rate of change in optic disc topography over time, and determine the effect of ocular hypotensive treatment on optic disc topography in ocular hypertensive patients. The ability of optic disc stereophotography and CSLO to detect glaucomatous optic disc change will be compared. 2. Race, optic disc topography and glaucoma susceptibility. To determine whether the higher incidence of POAG found in African American OHTS participants is due at least in part to a complex relationship among several factors including a larger optic disc area, larger changes in optic disc topography, higher measured IOP and thinner corneas. 3. Improving Prediction of POAG. To utilize baseline HRT topographic optic disc measures or changes in these measures to increase the precision and completeness of the OHTS risk model to predict POAG. Methods: Seven of the 21 OHTS study centers participate in this ancillary study;451 ocular hypertensive patients have consented to participate in the study. At least 352 (78%) are still active in the study with at least 5 years of follow-up on 324 participants. CSLO images are acquired annually at the dilated OHTS visit. The CSLO Reading Center at University of California, San Diego is responsible for processing and analyzing the images and providing the OHTS Data Coordinating Center with topographic optic disc data monthly. These data will be evaluated quantitatively for evidence of glaucomatous damage and change, and compared with structural and functional measures of primary open angle glaucoma endpoints obtained in the OHTS. This study will evaluate whether these advances in fundus imaging technology can improve the precision with which we can detect, predict and monitor glaucomatous optic neuropathy.